1. Field
Embodiments described in the present specification relate to a semiconductor memory device, and a method of performing a setting operation in the semiconductor memory device.
2. Description of the Related Art
In recent years, a resistance varying memory device employing a variable resistance element as a storage element has been receiving attention as a successor candidate of flash memory. Now, a resistance varying memory device is assumed to include not only narrowly-defined resistance varying memory (ReRAM: Resistive RAM) that adopts a transition metal oxide as a recording layer and nonvolatilely stores a resistance value state thereof, but also phase change memory (PCRAM: Phase Change RAM) that employs the likes of chalcogenide as a recording layer and uses resistance value information of a crystalline state (conductor) and amorphous state (insulator) thereof, and so on.
In a memory cell array of the resistance varying memory device, a memory cell including the variable resistance element is disposed at an intersection of a bit line and a word line. In such a memory cell array, selection of the memory cell can be performed using characteristics of the variable resistance element. In addition, by alternately stacking the bit line and the word line and arranging memory cell arrays to be stacked three-dimensionally, it is also possible to achieve a high-density memory cell array.
In the case of executing a voltage application operation on a selected memory cell to change its resistance state, if the selected memory cell has not changed to a desired resistance state by a certain operation time, then the voltage application operation is re-executed. In the case of repeating this re-execution of the voltage application operation while changing a voltage application time or voltage value until the selected memory cell changes to the desired resistance state, there is a risk that the operation time prolongs, an excessive stress is applied to the selected memory cell and the memory cell ends up deteriorating.